Known from DE 10 2009 034 095 A1 is a humidifier for a fuel cell which comprises a membrane stack including a plurality of membranes which are arranged one above the other and spaced apart from one another and between which flow channels are arranged. The membranes are designed to be water-vapor-permeable and enable water molecules to pass over from moist air, which is guided between two membranes, to a flow of dry air in a flow channel between adjacent membranes, which thereby is enriched with moisture. The moistened airflow is fed to a fuel cell system in which electricity is generated as a result of an electrochemical reaction.
In the stack, the membranes are connected in their edge regions to frame parts, wherein a sealing element for flow-tight closure is arranged between the frame parts of adjacent membranes. The dry or moist air flows crosswise through flow channels which are arranged one above the other and between which in each case one membrane is placed. The frame parts and the sealing elements therebetween also serve as spacers through which the membranes clamped in parallel are kept spaced apart from one another.